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15- Xerostomia.docx

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McGill University
PHGY 313
Russell Jones

Lecture 15 - The mouth, salivary glands, and the esophagus. 11/02/2013 Case Study: Xerostomia. Main symptoms: Lobulated dry tongue, dry gritty eyes, cannot produce saliva, impaired taste 1. How can salivary function be assessed? Illustrate the reflex pathway.  To measure how much saliva a person produces a day: 1. Put a pre-weighed sponge in the mouth. Saliva is considered 1:1 for g:mL (essentially water) 2. Put suction cup over Stenson's duct so saliva collects there. Stenson's duct is the main duct of the parotid gland which opens opposite the 2nd molar tooth inside the cheek. 3. Put 5% citric acid on tongue and measure volume of saliva that can be spat out into a graduated tube. 4. Scintiography: tests the function of the salivary glands. A radioisotope is administered and should be taken up by the salivary acinar cells via Cl- cotransporters. In Sjogren syndrome the uptake is slow, has a low peak value, and prolonged excretory phase (uptake is measured using a Geiger counter)  Sensory innervation of tongue o Ant 2/3 is VII, posterior 1/3 is the IX. Secretion is in response to these nerves, both parasympathetic and sympathetic. o Submandibular and sublingual glands are innervated by the lingual nerve and chorda tympani. o Parotid gland is innervated by IX. 2. Why is saliva important for dental health?  It provides continuous washing to stop bacterial growth (by destroying their cell walls, and by mechanical action.  Buffer acids since it's alkaline at high flow rates  Immune functions it contains antibodies, sialoperoxidase, thiocyanate, lysozyme.  Prevents demineralization of teeth via calcium phosphate  Without it: dental caries, gum disease, mucosal ulceration and atrophy, infection, can't use dentures well  Artificial saliva: Saliveze, xialine 1 & 2. Components of saliva? o Basic composition of any secretion starts as plasma. So the concentration of the ions must be isotonic to plasma at first. Capillaries surround the acini to interchange the ions/glucose. o Saliva is ultrafiltrate of plasma + α-amylase and mucins. Main ions are Na, K, Cl, HCO3, Mg, PO4-. It's hypotonic.  Note that K+ is not really present in plasma. Active transport must have occurred in the duct cells.  If you have time to produce saliva, there's high K. However if the rate of flow increases, the composition changes drastically. o Primary saliva the beginning of saliva. It's essentially isotonic to plasma o Secondary saliva   Unstimulated: The saliva you produce without food during the day just to lubricate your mouth.  Stimulated: The saliva that is stimulated by a meal. Fig 1: The change in composition of saliva vs. flow Glands  Parotid gland below and anterior to ear (secretes via Stenson's duct). o Secretion: watery with high content in a-amylase (
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